The present invention relates to a process for preparing a lower alkyl 4-(lower alkyl)-2-difluoromethyl-6-trifluoromethyl-3,5-pyridinedicarboxylate by a catalytic dehydrofluorination of a lower alkyl 2,6-bis(trifluoromethyl)-1,4-dihydro-4-(lower alkyl)-3,5-pyridinedicarboxylate.
The present rnvention provides a novel and useful process of dehydrofluorination of certain dihydropyridine compounds to produce certain pyridine compounds having a difluoromethyl substituent in the 2-position and a trifluoromethyl substituent in the 6-position. The process involves using a catalytic amount of a water soluble organic catalyst, together with a water soluble inorganic base dissolved in water. The dihydropyridine is dissolved in an inert organic solvent. The resulting pyridine product has demonstrated superior preemergence control of grassy weeds in transplant rice and both preemergence and early postemergence control of crabgrass on lawn and turf areas.